The first place in the continental United States where people were infected with the Zika virus through the bite of a local mosquito was in Wynwood, just north of downtown Miami. The Florida Department of Health confirmed the two local cases July 29, 2016. Florida’s first CDC-confirmed travel-related cases were in Miami-Dade and Hillsborough counties six months earlier.

The map below shows when the Florida Department of Health reported cases in each county. In late 2016, the department began including pregnant women and non-residents who were diagnosed in Florida in the state’s county and type-of-transmission totals. The categories listed are not mutually exclusive and cannot be added together.

With an abundant, almost year-round population of Aedes aegypti mosquitoes (the bloodsuckers capable of transmitting the illness) and a high volume of travelers from Zika-prone countries, the Sunshine State is especially vulnerable to an outbreak. In February 2016, the CDC began to issue weekly counts of cases reported by states and territories of laboratory-confirmed symptomatic cases. In February 2017, the CDC began issuing weekly counts of blood donors whose blood tested positive for the Zika virus regardless of being symptomatic. The categories listed are not mutually exclusive and cannot be added together.

The vast majority of Zika virus cases in the U.S. territories, particularly Puerto Rico, have been spread locally through Zika-positive mosquitoes and sexual transmission. The CDC reports weekly totals of symptomatic cases and Zika-positive blood donors regardless of symptoms. The categories below are not mutually exclusive and cannot be added together.

The Zika virus causes a serious birth defect called microcephaly — an underdeveloped brain and small head — and is linked to other neurological disorders in adults. Roughly 4 in 5 infected people are asymptomatic, but the disease’s most common symptoms are mild and include fever, rash, joint pain and red eyes.

The virus is primarily spread through mosquito bites and can also be transmitted through sex and blood transfusions.

A public health emergency of international concern was declared by the World Health Organization on Feb. 1, 2016, as the virus spread through Latin America and the Caribbean. WHO Director-General Dr. Margaret Chan declared the end of the emergency on November 18, 2016, and on February 1 she stated: “WHO and affected countries need to manage Zika not on an emergency footing, but in the same sustained way we respond to other established epidemic-prone pathogens.”

Severe birth defects

The CDC has confirmed the Zika virus causes microcephaly and other severe fetal brain defects. It can be passed from a pregnant woman to her fetus during pregnancy. The agency advises women who are pregnant or thinking of becoming pregnant not to travel to Zika-affected areas.

If a pregnant woman’s partner has been to such an area, the couple should abstain from sex or use condoms during the pregnancy. Currently, the CDC does not believe there is risk for the future pregnancies of a woman who has Zika once the virus clears from her blood.

Mosquito control is key

Zika is primarily spread to people through the bite of an infected Aedes aegypti mosquito — the same kind that causes dengue and chikungunya viruses.

To keep mosquitoes from multiplying, the Florida Department of Health recommends draining standing water once or twice a week. Garbage cans, bird baths and pool covers are all prime breeding grounds. Miami-Dade County residents can request a mosquito inspection or report a mosquito nuisance by calling 3-1-1.

The department also recommends using screens to cover doors and windows. To avoid bites while outside, cover skin with clothing and use mosquito repellent. Those with DEET, picaridin, oil of lemon eucalyptus, and IR3535 are effective. Florida has a Zika Virus Information Hotline managed by the Department of Health that can be reached at 1-855-622-6735.